A novel approach for voltage collapse analysis and control

This paper presents a systematic approach for power system voltage stability assessment and control. Unlike the conventional two-step procedure, it simultaneously solves the system differential and the algebraic equations at steady state to obtain the equilibrium solution, thereby removing all the unrealistic assumptions of slack and PV buses. Combined with a parameterized continuation technique, the methodology first identifies the system voltage collapse point during the direct equilibrium tracing, without rebuilding the system dynamic Jacobian and checking its singularity. Then, the voltage stability margin sensitivity is utilized to design an effective control strategy to mitigate voltage collapse. The detected voltage collapse point is proven being associated with a saddle node bifurcation in the rigorous sense of small-disturbance stability. The generator field and armature current limits are also accurately handled. Numerical test results with the New-England 39-bus system are presented to demonstrate the approach.